Fix startup segfault when the Mutex directive is used but no loaded

modules use httpd mutexes.

Add an init call from core's pre-config hook to ensure init is
performed before the config is parsed.

PR: 48787


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@912666 13f79535-47bb-0310-9956-ffa450edef68